Titan Power 8.4V 1700mAh NiMh Battery (AK Stick - Tamiya).
203mm long, 17mm thick, 17mm tall

NiMh:

• Low cost
  Nimhs are the most affordable type of airsoft battery available for new players with entry level airsoft devices just trying to get started on a budget.
  
  
• Generally Safe
  Nimhs carry less safety concerns than Lipo with a metal constructed body and less power overall, plus they won’t “puff” like a Lipo that off-gases when used improperly.
  
  
• Large Footprint
  Usually on the bigger side, especially when comparing to similar capacities, Nimh is often twice as large as their lipo and li-ion counterparts.
  
  
• Fewer Charge Cycles
  Nimhs have fewer charge cycles compared to lipos and li-ions, which in turn likely means that replacements will be needed more frequently. Consider li-ion for the longest life and lipo as a good high performance alternative.